Process utilizing moving solid catalyst



Ja n. 13,1949;

J. D. UPHAM PROCESS UTILIZING MOVING SOLID CATALYST Fil ed June 1, 194:5

- SPENT REGEENERATION so GAS s CASES 8 I COTTRELL, CYCLONE GASOLINE SEPARATOR PRECI PITATOR ADJ STABLE CA ALYST LEVELS CYC ON SEPA ATO REACTIVATED CATALYS as x )5 l4 SPENT 34/ CATALYST FRESH FEED l8 AIR &CY,CLE OIL INVENTYOR' J. o. UPHAM ATTO Patented Jan. 18, 1949 7 2,459,474 rnocnss u'rmzmo Movmc sou os'rsu's'r John D. um Bartleaville, th., asalgnor to Phillips Petroleum Company, a corporation of Delaware Application June 1, 194:, Serial No. 489,278

3 Claims. 1 This invention relates to a process and apparatus wherein material, such as a catalyst, is moved under conditions normally tending to cause corrosion and/or erosion of the apparatus. A specificmodiiication involves the prevention of corosion and/or erosion of the walls of reaction chamber, conduits, baiiles, or other portions of the apparatus wherein a mobile corrosive catalyst is employed.

In catalytic conversions utilizing liquid, and especially solid, catalysts in which the catalyst is suspended, dispersed, or dissolved in a flowing cially so where the catalyst itself. the reactants.

promoters, and/or products of reaction have a tendency to chemically attack walls of the reaction vessels and other equipment.

The invention has particular utility in hydrocarbon conversions where such problems are frequently encountered, and a preferred embodiment of the invention will be described with specific reference to a particular type of hydrocarbon conversion effected with a particular type of catalyst, namely the so-called fluid cracking of hydrocarbon oils, in which a finely powdered solid cracking catalyst is passed through the system. However, it will be seen that the principles of the invention may be applied to other processes and/ or apparatus wherein similar problems are encountered and the necessary modifications will readily be made by one skilled in the art in view of the detailed disclosure herein.

In the fluid cracking systems which have recently come into commercial use, solid cracking catalyst in the form of a powder, such as 200-400 mesh, iscontinuously passed through the apparatus at least partially suspended in hot gases. A hydrocarbon vapor carrying suspended catalyst powder is flowed through a conversion zone at cracking temperatures, usually in the range of 800-1150 F., spent catalyst is separated from 2 zone while suspended in hot oxygen-containing gases which eifect removal of carbonaceous matter from the catalyst by combustion, at temperatures from say 900 to 1400* F., and the active catalyst is separated from spent regeneration gases, purged, and returned to the conversion zone for re-use. A bed of the catalyst may be maintained in the lower portions of each zone, with said beds being continuously replenished by flow of catalyst into and from the lower part of the zone. In such instances the hot hydrocarbon vapors on the one hand and hot regeneration gas on the-other hand flow up through the beds and carry substantial amounts of the powdered catalyst in suspension into the upper parts of the chambers. This suspended catalyst is separated from eiliuent gases, and may be returned either to the same zone or to the other zone. In other cases. the reaction and regeneration zones may contain catalyst only in complete suspension in the gases. that is there is no bed of catalyst maintained. In either case, the catalyst flows through the system much as would a fluid, hence the name, and the particles continuously move through the equipment at elevated temperatures and in some places at least at fairly high velocities. As a consequence, in conventional practice appreciable erosion of equipment occurs both in the regeneration and reaction zones aswell as in conduits and other parts of the apparatus carrying streams of the solid catalyst particles.

Not only is the equipment itself worn away with consequent danger of failure which will at least force a shut-down for replacement and may result in a disastrous fire, but particles of undesirable extraneous material, usually I metal, becomes mixed with the catalyst and/or reactants.

Another method of cracking or otherwise converting hydrocarbons utilizing a mobile catalyst uses a moving bed of catalyst, and is exemplified by the so-called TCC method, ,wherein catalyst of fairly large particle size, such as 4-60 mesh, is caused to flow by gravity through reaction and regeneration chambers, generally counter-current to the gas flow therein. Usually the catalyst is lifted from the bottom of one chamber to the top of another by bucket-type chain elevators or the like. Rotary valves are provided for controlling inlet and outlet of catalyst to and from the chambers. Metal baffles ay be provided, particularly in the regeneratio chamber, to prevent channelling of catalyst. -In this type of system I I also, rather severe erosion problems are enusually have somewhat rough and angular surfaces which increase their erosivenese. Catalyistl used in such systems are manufactured in a manner which will give them as hard a structure as possible, consistent with suitable porosity and activity, in order to minimize attrition losses, and thus are even more erosive than might otherwise be the case.

In addition to overcoming the aforementioned problems, my invention may, in certain instances, at the same time serve to provide a desired amount of catalyst make-up -to a system utilizing powdered catalyst.v In some modifiications. I may provide for control of heat transfer in catalytic systems. Various other advantages of the invention will become apparent as the disclosure proceeds.

It is an object of this invention to provide improved apparatus and process wherein erosion and/or corrosion by moving material is minimized. Another obiect is to provide apparatus suitable for eflecting hydrocarbon conversions utilizing a mobile solid catalyst. A further object is to provide improvements in so-called "fluid" catalyst systems wherein difficulties arising from erosion caused by hard catalyst particles moving through the system are mitigated. A further object is to provide powdered catalyst make-up into such a system. An important object is to avoid introduction of finely divided extraneous matter, particularly metal, into mobile catalyst systems. Yet another object is to provide for the determining of the rate of wear of protective surfaces or the like. Other objects of the invention will be apparent from the accompanying disclosure and discussion.

Briefly. my invention comprises in preferred modification the combination of equipment suitable for eifecting catalytic conversions through the agency of a mobile solid-catalyst composition, together with a protective coating on portions of said equipment normally subject to corrosion or erosion by the moving catalyst, said coating being made of one or more components of the catalyst composition itself. The protective coating is desirably compacted into a hard or dense form, as contrasted with the normally porous structure of the catalyst. Not only does this coating protect the fabricated metal or other parts of the app ratus completely from the deleterious action of the moving catalyst hereinbefore referred to, but impingement or abrasion of the catalyst particles against the coating causes only a component of the catalyst composition, rather than extraneous material, to be in-' troduced into the system. Such catalyst component so introduced by action of the moving catalyst on the protective coating is innocuous in the reaction mixture and equipment, since it is.-

a normal component of the reaction mixture, and in some cases may even be turned to considerable advantage as will appear more fully hereinafter; this is to be contrasted with the undesirable and sometimes highly injurious introduction of abraded materials of construction which would otherwise occur.

The invention may be more fully understood by reference to the accompanying drawing which shows somewhat diagrammatically in partially cut-away view a preferred arrangement of apps.- ratus suitable for carrying out the "fluid catalytic cracking of gas oil. The drawing and accompanying description will thus serve'to exemplify one mode of application of the invention. A- reaction chamber In and a regeneration chamber l2, of somewhat similar or identical active catalyst enters reaction chamber l through line 14 and distributor II, and deactivated catalyst flows out of chamber l0 first by gravity through line l6, and then, by the gas-liftaction of air or other regeneration gas introduced via line I8, upwardly through line 20 and distributor 22 into regeneration chamber I2.

The regenerated catalyst in turn-flows out of chamber l2 by gravity through line 24 and then upwardly through line II by virtue of the gas-lift action of the hydrocarbon feed introduced into line ll via line 26, and on into chamber l0 through distributor ii for again catalyzing the cracking reaction. It will be seen that a continuous feed of active catalyst and hydrocarbon reactants is thus supplied to the reaction zone,

while oxygen-containing gas and deactivated catalyst are continuously supplied to the regeneration zone.

The fresh feed to the system, in this case a Mid-Continent gas oil of 35 A. P. I. gravity, enters the system via line 28 and is passed into fractionator 30 at a point intermediate the top and bottom thereof. '0 also enter fractionator 30 via. line 32 at a lower point. These hot effluents comprise products of the cracking reaction, including gas and gasoline, and unreacted or partiallyreacted material boiling above the gasoline boiling range, generally termed cycle oil. In the arrangement shown, fractionator 30 is so operated that the kettle product therefrom, which passes via lines 34, 26, and It to reactor III, comprises this cycle oil and also the fresh food introduced via line 28, while the gasoline and lighter fractions are taken overhead via line 36 to conventional I fractionation means not shown for additional separation into desired fractions or products. A substantial amount of the sensible heat of the eilluents from chamber I0 is thus imparted by direct heat exchange to the incoming fresh feed, which in turn may act as a refluxing medium in fractionator 30. Additional kettle heating and reflux cooling for fractionator 30 may be provided as required by conventional means indicated diagrammatically by heating coil 38 and cooling coil 40. The total feed to reactor l0 passing through lines 34 and 26 may be heated additionally by conventional means not shown, or. heat contained in the regenerated catalyst in line I may be suflicient to vaporize and heat this feed to reaction temperature. Various other means of conserving heat and effecting heat transfer between feed, eilluents, catalysts, etc. may of course be utilized as desired in connection with the system.

Hydrocarbons introduced into the reaction chamber pass upwardly through a. loose bed of the catalyst 41 maintained in the bottom of the chamber, and then up through the free space in the upper part of the chamber carrying substantial quantities of catalyst in suspension. The level of the catalyst bed, indicated by reference numeral 42, is readily adjusted to any desired height, and in correlation with rate of hydrocarbon feed, temperature, catalyst to hydrocarbon ratio, and other reaction conditions, acts to govern the extent of conversion obtained. This bed is not static, but rather is continuously flowing much as would a liquid, being supplied with Hot efiiuents from reactor 8 fresh catalyst introduced along with hydrocarbon feed through line I4 and distributor ll, while spent catalyst is flowing out through line II for regeneration. vigorous agitation due to the iiow oi-liydrocarbons therethrough and the very light weight oi.

Oicoursethebedisinastateoi.

of most gas oils to obtain optimum yields of highoctane-number motor fuel, the reaction temperthe individual catalyst particles, a"iair proportion of which are carried into the upper portion of chamber II in suspension in the gaseous hydrocarbons. This suspension leaves the top oi chamber It through line 44 and enters cyclone separator l! or its equivalent, wherein almost all of the suspended catalyst is separated irom the hydrocarbon ases. which pass via line 32 into iractionator it as heretofore" discussed, while the separated catalyst is returned to chamber il through line 4|. Any small amounts oi catalyst powder escaping irom separator 40 through line I! may be separated by means, not shown, such as electrical precipitation or other methods known to the art, or may be separated in iractionator I and obtained in the liquid kettle product in suspension therein and thus reintroduced into chamber II.

The catalyst utilized in cracking zone It becomes deactivated by deposition of carbonaceous matter thereon and hence must be regenerated. This is accomplished continuously by withdrawing catalyst from chamber iii by means of line 16, and introducing same into regeneration chamber l2 via line II 'and distributor II. In chamber II, the carbonaceous matter is removed from the catalyst by oxidation with air or other oxygencontaining gas introduced through line it. The

liow of catalyst in chamber I1 is similar to that in chamber ill: a flowing bed is maintained, the level of which is indicated at it, reactivated catalyst is continuously withdrawn via line 24 for reuse in reaction chamber II, and a suspension of catalyst in regeneration gases is withdrawn via conduit I2 and introduced into cyclone separator II. In separator 84 most of the catalyst ature will generally be from 850 to 1050" F., the pressure from atmospheric up to 50 or 100 pounds per square inch, the residence time of reactants within' the reaction zone from 5 to 50 seconds, and the weight ratio oi catalyst to oil ted to the reaction zone will range from a value 01 about 0.5:1 to about :1. The extent of conversion per pass may be relatively low, such as from 10 to per cent, .in which case a recycle oi unconverted and/or partially converted oil is used, or it may be higher, the once-through type of operation usually obtaining 50 per cent or greater conversion per pass, in which case little or no recycle is used. Cycle oil in this case is usually passed to non-catalytic cracking'i'or better utilization. In the arrangement shown in the drawing, most of the cycle oil is returned for re-treatment. However, continued recycle would finally produce a material quite resistant to further catalytic cracking: accordingly,- a continuous draw-oi! of a portion of such material is provided, as by line 88. Other methods of accomplishing the same result are well known to the art, and need not be considered here. In the present example, with a 20 per cent conversion per pass, an ultimate conversion of about 70 per cent to products boiling outside the range of the gas oil feed stock is obtained, with the motor uel product amounting to about 65 volume per ce t oi the feed stock.

Regeneration oi the catalyst is accomplished at combustion temperatures which are preferably not in excess of about 1400" F.in any case, and which with some catalysts should not exceed 1050 to 1100 F. This temperature will be dependent on the amount of carbon deposited on the catalyst, as well as the temperature and volume of oxygen-containing gas utilized for eiIecti'ng the is separated and returned via line it to regenerator l2, while the regeneration gases exit via lines It and II. If necessary, a Cottrell precipitator N or other means may be interposed for the purpose of recovering traces oi catalyst not separated in unit 54. Such recovered catalyst may be removed via line 82 and if desired returned either to zone ill or zone I2 by means not shown.

Inasmuch as it is desirable to purge spent catalyst of. hydrocarbons admixed with or adsorbed thereon prior to its introduction into contact with oiwg'en-containing gas, steam or other inert gas may be introduced into conduit it via line 84. This purge gas is caused to flow into reaction chamber l0 countercurrent to the catalyst, car.- rying with it material purged from the catalyst which is thus returned to the reaction zone, while the purged catalyst continues on toward regeneration chamber II. In like manner, oxygen-containing gases and oxygenated material are purged from regenerated catalyst by introduction of a steam purge into conduit 24 through line It.

This purge may also serve to cool the catalyst somewhat if desired. Conduits 2i and I may be somewhat enlarged at or near the point of steam introduction or otherwise modified to facilitate the counter-current movement of steam and catalyst without substantially impeding catalyst now. I

Reaction and regeneration conditions may of course be chosen within a rather wide range, and will depend largely on the particular stock being oxidation. Since the catalyst itself has. a substantial heat-carrying capacity, a relatively high catalyst to oil ratio is frequently used so that the ratio of catalyst to carbon thereon is sufficiently high as to avoid too great a temperature rise in the regeneration chamber. Other means of controlling temperatures, including indirect cooling, use of cool inert gas such as steam, excess air, etc. may also be used as deemed advisable for a given set of conditions.

Regardless of how rugged and heat-stable the catalyst may be, it gradually loses activity, so that a. portion must be intermittently or continuously withdrawn from the system. and replaced by freshly manufactured catalyst. Such withdrawal may be through line 88 and/or line It or line 82. Make-up catalyst may be introduced by means not shown, or may be provided through the practice of my invention as will be described more fully hereinbelow.

Turning now to the particular construction of the apparatus embodying features of my invention, portions of reaction chamber iii are shown cut away in the drawing to reveal an outer metallic shell 10, having a protective inner coating 12. This protective coating is composed of the same material as the catalyst. For example, in this instance where a synthetic silica-alumina powder is being utilized as catalyst, the coating 12 is also made from this material. It will be appreciated that only a very small proportion.

ii any, of the conversion is eil'ected by virtue of cracked and the catalyst used. In the cracking 7 per unit oi weight and its intimate admixture with reactants. Thus the protective coating of the instant invention, although composed of a component or all components of the catalyst, is effective primarily when utilized in conjunction with systems designed specifically for the utilization of mobile catalysts such asthose described herein, and functions to protect parts of the apparatus normally adversely affected by action of the mobile catalyst, and in other special ways as disclosed herein.

In addition to the inner walls of the reaction chamber I0, other parts of the apparatus are similarly coated, particularly the inner walls of conduits carrying the catalyst alone or in suspension, and the cyclone separators. It will be seen that it is in these conduits and in the cyclone separators that the catalyst particles move with the highest velocities, and undergo changes of direction whereby certain areas in particular are subjected to impingement of a large number of the rapidly moving solid particles. Portions of conduits 44, 4B, and 20, and cyclone separator 46 are shown cut away in the drawing; revealing protective coatings indicated by the numerals 14, I6, 18, and 80 respectively. Baiiles in the separator are also covered by the coating. The regeneration chamber l2 and conduits and cyclone separator associated therewith are similarly protected.

A particularly useful function of my protective coating is that it not only protects the apparatus against erosive and/or corrosive effects of the moving catalyst, but also may be so applied as to provide substantial insulation of the outer shell or other part of the apparatus against the high temperatures prevailing within said apparatus. This is especially advantageous in conduits, since it is generally desirable to minimize heat losses therefrom. This internal insulation means that the outer shells need not be fabricated to withstand the high temperatures to which they normally would be subject, with consequent savings in valuable metals, or the provision of greater safety for a given construction. The shells or the like may also be constructed from ordinary materials rather than special alloys,

since they are not subject to the normal erosion To this end,

avoided. One of two methods is ordinarily utilized in preparing these protective coatings. The linings of chambers, conduits, return bends, cyclone separators, and the like may be prefabricated to the proper size and shape and then put into place. This has the advantage of a simpler control of fabrication conditions, with equipment especially adapted thereto. However, they may also be placed in situ, particularly on irregular surfaces, as by spraying, plastering, or other suitable techniques which will be readily understood. The lining material need not be of exactly the same composition as the catalyst, but will be approximately the same, or will at least comprise a component of the catalyst, as disclosed herein. Binders, fillers, lubricants, or other such material which is innocuous in the system may 8 be admixed therewith in minor amount to facilitate manufacture and/or to improve the mechanical strength and/or .resistance to abrasion. Frequently the catalytic component is mixed with water, or other liquid, formed into desired shape or applied to the surface in question under substantial pressure, and then calcined. As an example, -in-the case of silica-alumina catalysts, a hydrated silica is prepared having a considerably higher silica content than that used in preparing the mobile catalyst proper. This hydrated silica, either alone or activatedwith minor amounts of adsorbed or co-precipitated alumina, may if desired be admixed with from 1 to 15 per cent of finely powdered graphite, gypsum, or other filler or binder, appliedto the surface to be protected under about 1000 poundspressure, and then slowly heated and dried to a water content of say 15 to 25 per cent. At this point another coating of the same material may be applied, or the heating may be continued to a temperature somewhat above those to be encountered during operation. The high silica content of the original hydrogel aids in producing a relatively dense protective coating which has relatively little catalytic effect per se in the apparatus compared to that of the moving catalyst powder, but small particles abraded from this coating by the moving fluid catalyst have a catalytic activity approaching that of the catalyst proper and sufiicient to provide a portion of the normal catalyst make-up for the system described. The coating is applied to a depth such that the final thickness is usually at least one inch and may be greater at points of greatest wear. and/or where its thermal insulative value is of importance.

The apparatus is constructed to facilitate replacement of the protective coating wherever and whenever required. In order to determine when this is necessary, I may advantageously embed a thermocouple, resistance thermometer,

or similar th'ermo-sensitive means in the coating at one or more points subjected to greatest wear. The thermocouple 82 is shown in the drawing embedded in the lining of cyclone separator 46. Preferably it is fairly deep in the coating, that is near the metal wall of the separator. An indicator 84 such as a potentiometer, shows the temperature of the thermocouple, which will of course vary with the thickness of coating between it and the contents of the separator. As this coating wears away, the indicator will show an increasing temperature, and one may readily determine, by preliminary calibration or otherwise, at what point the protective coating is sufficiently worn away to expose the thermocouple or to require replacement. This particular arrangement is very useful in this connection, and

may of course be utilized in other situations for measuring or determining total amount of wear or rate of wear of a surface or body.

While described with particular reference to the fluid" cracking of hydrocarbons, the inven-. tion may be applied to other chemical conversions carried out with similar methods of contacting catalyst with reactants. It may also be applied to moving-catalyst-bed cracking or other conversions, in which the grinding action of the granular catalyst is frequently found to be quite severe in conventional installations. Among other systems to which my invention may be applied may be mentioned, merely by way of example, isomerization or other conversions of hydrocarbons wherein a catalyst composition comprising arcane an active metal halide, such as aluminum chloride, along with a finely divided solid inorganic filler or promotermaterial, such'as brucite, bauxite, magnesia, alumina, other naturally occurring or synthetically produced metal oxides, magnesite, asbestos, Iullers earth, bentonite, talc, etc. is utilized in the form of a slurry which is circulated in or through a reaction zone in admixture with hydrocarbons. Patent application Serial No. 442,269 by W. A. Schulze, now U. S. Patent No. 2,374,507 issued April 24, 1945, discloses such an isomerization system. In such case the component of the catalyst composition chosen as protective material is usually the metal oxide or other solid material used as support or extender for the more active metal halide component of the catalyst. This minimizes corrosion and erosion of metal or other equipment, which is particularly severe with active metal halide catalysts, and also may be utilized to-prevent introduction of undesired iron or other metal compounds into the system, which, especially in the case of aluminum chloride-containing catalysts, normally greatly diminishes catalyst activity and life. As another example may be mentioned the recovery of dioleflns by contacting a diolefin-containing stream with finely divided cuprous chloride or other halide ot a heavy metal of Group I or II of the periodic system, as disclosed in patent application Serial No. 478,427 by I. L. Wolk, now U. S. Patent No. 2,386,734 issued October 9, 1945. A cuprous halide-diolefin complex is formed, separated, and decomposed in suspension in an inert gas to recover the pure diolefin and the cuprous halide. In this instance the parts of the apparatus particularly subject to erosion may be coated with the cuprous halide, preferably in dense form. Yet another example to indicate the possible scope or my invention is the adsorption of certain constituents of a gas mixture by solid adsorbents such as activated charcoal, silica gel, activated alumina, and the like, wherein the solid particles are moved through the system. Other applications of the principles of the invention will be obvious to those skilled in the art in view of the detailed disclosure herein.

I claim:

1. In a catalytic conversion process wherein a moving powdered porous catalyst prepared from a silica hydrogel activated with minor amounts of alumina is utilized, the method of preventing the introduction of extraneous matter into the reaction system through erosion or corrosion of portions of the apparatus caused by action of the moving catalyst, while maintaining a desired substantially constant level of catalytic activity. which comprises preparing a hydrated silica having a substantially higher silica content than that Number Name Date Re. 10,382 Alsing Sept. 18, 1883 1,574,935 Pyzel Mar. 2, 1926 1,903,568 r Goldsborough Apr. 11, 1933 1,957,051 Norton May 1, 1934 2,056,732 Mekler Oct. 6, 1936 2,094,946 Hubmann Oct. 5, 1937 2,129,174 Hancock Sept. 6, 1938 2,209,075 Davis July 23, 1940 2,239,801 Voorhees Apr. 29, 1941 2,264,968 De Forest Dec. 2, 1941 2,276,883 Shon et al. Mar. 17, 1942 2,288,613 Dill July 7, 1942 2,293,946 Payne Aug. 25, 1942 2,327,175 Conn Aug. 17, 1943 2,340,878 Holt et al. Feb. 8, 1944 2,350,759 Hilmer et a1. June 6, 1944 FOREIGN PATENTS Number Country Date 7,505 Great Britain 1915 23,045 Great Britain 1910.

used in preparing said mobile catalyst, activating same with minor amounts of alumina, applying the thus treated hydrogel under about 1000 pounds pressure to the surface of an apparatus element normally erodable by action 01 the moving catalyst, slowly heating the thus-applied material to a temperature above those employed in the conversion to produce a hard, dense compacted protective coating for said element having littlecatalytic activity at the surface compared to said-mobile catalyst but having substantial catalytic activity when com'minuted, contacting said powdered porous catalyst with reactants at conversion conditions, effecting movement of said powdered porous catalyst such that said protective coating is eroded to an extent sufficient to provide at least a portion. 01 the make-up powdered catalyst required in said process in the form of catalytic powder abraded from 'said coating, and removing from the process an amount of powdered catalyst at least'equivalent to the make-up catalyst thus supplied, to maintain a desired level of catalytic activity.

2. The method of claim 1 in which said conversion process is a conversion of hydrocarbons.

3. The method of claim 1 in which said conversion process is the cracking or hydrocarbons at temperatures in the range or 800 to 1150F.

JOHN D. UPHAM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED sTATEs PATENTS Certificate of Correction Patent No. 2,459,474. January 18, 1949.

JOHN D. UPHAM It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 4, line 39, for the Word food read feed column 7, line 44, after "safety insert factors; line 50, for coating read coatings;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 2nd day of August, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommissioner of Patents. 

